201102340 •六、發明說明: •【發明所屬之技術領域】 本發明係有關一種多層微結構之製造方法,特別是一種可平衡殘 留應力之多層微結構製造方法。 【先前技術】 近來,微機電系統(Microelectromechanical Systems, MEMS)裝置 ^ 例如壓力感測器、麥克風、氣體感測器、加速感測器、共振器、微鏡 面及生物感測器等,發展以成熟之半導體工業製程例如互補金氧半導 體(Complementary Metal Oxide Semiconductor, CMOS)製程製作。因 此,MEMS裝置之微結構(Microstructure)可與其積體電路以單一 CMOS製程完成’以降低成本。一般半導體工業之多層cmos製程 中使用之矽、多晶矽、金屬内連線及介電層等,均可用以形成 CMOS-MEMS裝置之微結構。 接著,於CMOS後製程中,進行一蝕刻步驟,以形成懸置之微結 構於基材上。蝕刻步驟可以使用濕蝕刻或乾钱刻技術進行。其中,濕 • 蝕刻之蝕刻率與選擇性均較佳,但因有殘留蝕刻溶劑附著於基材表面 及懸置之微結構底部表面,而使姓刻溶劑之表面張力造成微結構與基 材互相黏著的現象。因此,為了避免黏著現象,可選擇使用乾姓刻技 術。乾姓刻技術又可分為錢擊姓刻(Sputter Etching)、反應性離子钱刻 (Reactive Ion Etching,RIE)及電漿蝕刻(Plasma Etching),其中,濺擊蝕 刻係使用離子研磨(ion milling)蝕刻物(Etchant),屬物理性蝕刻,為非 等向性蝕刻但對蝕刻物之選擇性低;電漿蝕刻使用反應氣體與蝕刻物 產生化學反應,屬化學性蝕刻,為等向性蝕刻並且對蝕刻物之選擇性 高;反應性離子蝕刻使用反應氣體與蝕刻物產生化學反應,並以離子 研磨蝕刻反應產物,介於濺擊蝕刻及電漿蝕刻間,為非等向性蝕刻且 對蝕刻物選擇性高。因此,習知技術一般使用RJE,利用其非等向性 201102340 敍刻性質以形成高寬高比(aspect ratio)之微結構。201102340 • VI. Description of the invention: • Technical field to which the invention pertains The present invention relates to a method of manufacturing a multilayer microstructure, and more particularly to a method of fabricating a multilayer microstructure capable of balancing residual stress. [Prior Art] Recently, microelectromechanical systems (MEMS) devices, such as pressure sensors, microphones, gas sensors, acceleration sensors, resonators, micro-mirrors, and biosensors, have matured. The semiconductor industry process is, for example, a Complementary Metal Oxide Semiconductor (CMOS) process. Therefore, the microstructure of the MEMS device can be completed in a single CMOS process with its integrated circuit to reduce cost. The CMOS, polysilicon, metal interconnects, and dielectric layers used in the multi-layer CMOS process of the semiconductor industry can be used to form the microstructure of CMOS-MEMS devices. Next, in a post-CMOS process, an etching step is performed to form a suspended microstructure on the substrate. The etching step can be performed using wet etching or dry etching techniques. Among them, the etching rate and selectivity of the wet etching are better, but the residual etching solvent adheres to the surface of the substrate and the bottom surface of the suspended microstructure, so that the surface tension of the surnamed solvent causes the microstructure and the substrate to interact with each other. Adhesive phenomenon. Therefore, in order to avoid sticking, you can choose to use the technique of dry surname. The dry name engraving technique can be divided into Sputter Etching, Reactive Ion Etching (RIE) and Plasma Etching, in which the etch etching uses ion milling (ion milling). Etchant, which is a physical etch, is an anisotropic etch but has low selectivity to the etchant; plasma etch uses a reactive gas to chemically react with the etchant, is a chemical etch, isotropic etching And the selectivity to the etchant is high; the reactive ion etching uses a reaction gas to chemically react with the etchant, and etches the reaction product by ion milling, between the splatter etching and the plasma etch, and is anisotropic etching and The etchant has high selectivity. Therefore, conventional techniques generally use RJE, utilizing its anisotropy 201102340 to characterize the microstructure to form a high aspect ratio microstructure.
圖la、圖lb及圖lc所示為習知技術製作(:]^〇5_]^]^裝置1〇〇 之流輕剖面圖。於CMOS製程中,如圖ia所示,形成CM〇s電路 120及多層微結構130於基材110上。其中,多層微結構13〇包含介 電層ill與圖案化之金屬層131彼此交互堆疊,且圖案化之金屬層m ,此之圖案相互對稱,形成蝕刻通孔132。金屬層131係利用CMOS 製程中-,用以作為金屬内連線之第一金屬_故丨υ、第二金屬⑽咖 2)、第三金屬(Metal 3)與第四金屬(MetaM)。基材11〇與介電層⑴ 之材料分別主要包含石夕與二氧化石夕。於CM〇s後製财:如圖曰化所 不,以金屬層131為遮罩,使用三氟甲院(CHF3)與氧氣生成反應離子, 以進行非等向性腿_介電層⑴至露出基材ιι〇。接著,如圖k 所不,使用六氟化硫(SF6)與氧氣生成反應離子,以對基材11〇進行較 為等向之·_,形成一懸置之多層微結構130,。 又 I請參閱圖1c,相鄰之金屬層131與介電層⑴間,因豆有 係數’喊生前應力。當介電層具有上下對稱之金屬層時,= $下層金麟射電層之朗應力較可相互平衡,反之,則益 Γ結構。細,如圖卜所示,最下層之介電層⑴,Μ 層it 無法由非等向性㈣移除,形成非對稱之懸置多 軔曲银°务 於基材110上,因而使殘留應力造成較嚴重之微結構 I曲見象,如圖2所示,改變 電性特徵。 $ 裝置之機械特徵,進而影響其 為解決上述問題,本發明揭示_ 製造方法,其使懸置之多層微結 禮之夕層微結構 殘留應力,而保持MEMS裝置之^旦垂直方向具結構對稱性,以平衡 201102340 【發明内容】 法,施例提供—種可平衡殘留應力之多層微結構製造方 微結構二:H先,形成一多層微結構於一基材上。此多層 層。其中 、屬層、一金屬中介層、-第二金屬層與-絕緣Figure la, Figure lb, and Figure 1c show the flow profile of the device (1)^〇5_]^^^ device. In the CMOS process, as shown in Figure ia, CM〇s are formed. The circuit 120 and the multilayer microstructure 130 are on the substrate 110. The multilayer microstructure 13 includes a dielectric layer ill and a patterned metal layer 131 alternately stacked with each other, and the patterned metal layer m is symmetric with each other. An etch via hole 132 is formed. The metal layer 131 is made of a CMOS process, and is used as a first metal of a metal interconnect wire, a second metal (10) coffee 2), a third metal (Metal 3), and a fourth metal. Metal (MetaM). The materials of the substrate 11〇 and the dielectric layer (1) mainly include Shi Xi and the dioxide dioxide, respectively. After the CM〇s, the money is made: as shown in Fig. 2, the metal layer 131 is used as a mask, and the reactive ion is generated by using the trifluoroethylene (CHF3) and oxygen to perform the anisotropic leg-dielectric layer (1) to Exposed substrate ιι〇. Next, as shown in Fig. k, sulfur hexafluoride (SF6) is used to generate reactive ions with oxygen to form a suspended multilayer microstructure 130 on the substrate 11?. See also Fig. 1c, between the adjacent metal layer 131 and the dielectric layer (1), because the beans have a coefficient 'shocking pre-stress. When the dielectric layer has a vertically symmetrical metal layer, the lang stress of the lower layer Jinlin radio layer can be balanced with each other, and conversely, the structure is beneficial. Fine, as shown in Fig. Bu, the lowermost dielectric layer (1), the it layer it cannot be removed by the anisotropy (4), forming an asymmetric suspension of the multi-curved silver on the substrate 110, thus leaving the residue The stress causes a more severe microstructure I to appear, as shown in Figure 2, changing the electrical characteristics. The mechanical characteristics of the device, which in turn affects the above problems, the present invention discloses a manufacturing method that allows the suspended microlayers to have a microstructural residual stress while maintaining the structural symmetry of the MEMS device in the vertical direction. Sexuality to balance 201102340 [Invention] The method provides a multilayer microstructure for balancing residual stress. The microstructure is: H first, forming a multilayer microstructure on a substrate. This multi-layered layer. Wherein, a genus layer, a metal interposer, a second metal layer and an insulation
由絕緣層堆層與第二金屬層⑽緣_隔’第_金屬層並藉 制I f材上;第—金屬層與第二金屬層並圖案化形成複數 門:H圖案化對稱性結構;並且,第-金屬層與第二金屬層 =金屬中介層,包圍每一刪孔,且絕緣層填滿每一甜刻通 者’進行—等向性化學《_步驟,以金屬層及金屬中介層 π ’移除伽丨通孔内之絕_,及第—麵層與储間之絕緣 S开/成1置之多層微結構於基材上。此懸置之多層微結構在垂直 方向具結構對稱性’可平衡殘留應力,有效抑她曲問題。 本發明一實施例使用較低真空度之腔體壓力,達成等向性之化學 電漿姓刻,並調整反應氣體之比例,以提高蝕刻率。 【實施方式】 圖3a、圖3b及圖3c所示,為本發明之可平衡殘留應力之多層微 構裝造方法一實施例之流程剖面圖。本發明之可平衡殘留應力之多 層微結構製造方法包含下列步驟。請參閱圖3a,形成一多層微結構 330於一基材310上。於一實施例中,多層微結構33〇包括:複數金 屬層33卜金屬中介層333及絕緣層311。 接續上述,請同時參閱圖3a與圖4。圖4所示,為多層微結構最 上層之金屬層33Id之側視示意圖,而圖3a為圖4中(沿剖線AA’之 結構剖面圖)。其中,複數金屬層331包含第一金屬層331a、第二金 屬層331b、第三金屬層331c與第四金屬層331d,為一圖案化對稱性 結構,金屬層331a、331b、331c、331d上互相對稱之圖案形成複數 個蝕刻通孔332。請同時參閱圖3a、圖5a與圖5b。圖5a與圖5b所 201102340 • 示,為多層微結構二實施例之俯視透視示意圖。金屬中介層333係設 置於金屬層331a與331b、331b與331c、331c與331d之間,圍繞每 一蝕刻通孔332。如圖3a所示,絕緣層311填滿蝕刻通孔332,金屬 層33la、331b、331c與331d間之間隙,並使第一金屬層33la藉由 絕緣層311堆疊於基材310上。 請參閱圖3a,於一實施例中,多層微結構330係以CM〇s製程 製作,金屬層331a、331b、331c與331d分別使用金屬内連線 (Interconnect)之第一金屬(Metal 1)、第二金屬(Metal 2)、第三金屬 (Metal 3)與第四金屬(Metal 4);金屬中介層333係使用金屬内連線之 ® 中介(Vla)層;絕緣層311使用包含隔離金屬内連線之介電層311a,及 隔離CMOS電晶體之場氧層311b以覆蓋基材310。並且,於一實施 例中,絕緣層311與基材310之材料主要分別為二氧化矽(Si〇2)盥矽 (Si)。 ’、 接著,進行一等向性化學電漿蝕刻步驟。如圖3b所示,蝕刻時 係以最上層之金屬層331d及金屬中介層333為遮罩,移除餘刻通孔 332内之絕緣層311,但保留部份金屬層331&、33比、33化與 間之絕緣層311,以維持微結構之堆疊。 • 再來’如圖3c所示,繼續進行等向性化學電魏刻步驟以完全 移除第-金屬層331a與基材31〇間之絕緣層M1,及部分基材31〇, 乂开/成懸置之多層微結構33〇’ ,其金屬層331兩兩對稱,使絕緣 層311與其上下金屬層331間之殘留應力大致相互平衡。對雛多層 微結構可最少由二層金屬層構成,再來為三層金屬層,並以此類推。 於上述之實施例中,欲侧之材料為⑽與&,因此,化學電浆 氣Z驟採用版1匕物氣體及氧氣(〇2)為反應氣體。氟化物氣體可為四 二%(CF4)、六氣化二碳(C2F6)等敦化碳(Flu〇r〇Carb〇n)氣體,用以提 氧η原子與氟自由基。將氟化碳之電漿加入少量〇2,使碳(c)與 。而釋出氟(F)中性原子與氣自由基,可有效提高餘刻率, 201102340 但〇2之濃度太高,會造成覆蓋於欲蝕刻材料表面,導致蝕刻率下降。 以下實施例以CF4與〇2氣體為反應氣體,以說明本發明如何決定〇2 與CF4之氣體比例’但非用以限制本發明。圖6為ο:與cf4氣體之 氣體比例與蝕刻率(EtchingRate,ER)之關係圖,其中Si蝕刻率(ER)之 圖例為方形,對應左側縱軸刻度,Si〇2蝕刻率(ER)之圖例為三角形, 對應右側縱轴刻度。由圖6可知,當〇2於CF4氣體中之濃度係介於 10%〜40%時,相較於其它濃度對Sl〇2有較高之蝕刻率,而其中以濃 度大約為23%時蝕刻率最高。當〇2於eh氣體之濃度係介於5%〜1〇% 時,相較於其他濃度對Si有較高之蝕刻率,其中以濃度大約為1〇% • 時蝕刻率最高,但假使需考量蝕刻時對Si與Si〇2之選擇性,則於濃 度為5%時較佳,因其對Si與Si〇2之蝕刻率(ER)比例較高。 、丨 化學電漿蝕刻步驟一實施例係以調節腔體壓力達成等向性蝕 刻》等向性蝕刻係指側向蝕刻率(ERa)與縱向蝕刻率(ERb)大致相同, 即蝕刻之等向效柳tchingRateRatio^ERR^)趨近於i。蝕刻之等向 效果(ERR-係定義為側向蝕刻率(ERa)與縱向餘刻率(E叫之比。圖7 所不’為腔體塵力(Chamber Pressure,CP)對於Si〇2之餘刻之等向效 果(ERIW與縱向蝕刻率(ERb)之關係圖,其中,餘刻之等向效果卿y 之圖例為方形,對應左側縱轴之刻度,縱向飯刻率(孤)之圖例為三角 擊形,對應右側縱軸之刻度。如圖7中峨之姓刻率㈣曲線所:, 麟腔體壓力(CP)減少,即腔體真空度提高,侧率(ERb)越高。因此, 般而3,電漿姓刻技術為提高敍刻率,將反應腔體維持在較高之真 空度。然而,如圖7 t Si〇K_之等向效果(膽曲線所示,隨 者腔體壓力(CP)增加,即腔體真空度降低,_之等向效果(舰^ $趨近1。因此’為提升侧之等向效果(舰一,反應腔體需維持在 較低之真线。於本實施财,為舰狀等向效果(腿^介於〇 w 之間,腔體勤(CP)之範圍係設定介於〇 25〜〇 7邮〇啦間。於一 ’較低之腔體真空度係透過於抽真空幫浦办师)之進氣端加 裝一手動閥門(Valve) ’以降低幫浦之抽氣能力,讓幫浦抽氣與通入的 201102340 氣體流量在較低的真空中達到平衡。 等向性化學電漿蝕刻步驟所需時間可由欲蝕刻之si〇2之厚度,及 蝕刻率決定。請參閱圖3a,於一實施例中,多層微結構33〇係以TSMC 0·35μπι製程製作,其中,第一金屬層331a、第二金屬層331b、第三 金屬層331c與第四金屬層331d分別使用MetaU、Metal 2、Metal 3 與撕故1 4金屬内連線,高度分別為6650 A ' 6450 A、6450 A與 9250 A ;金屬層331a、331b、331c、331d間之金屬中介層333高度 均為Ιμιη,因此介電層311之厚度亦為ιμιη ;而場氧層312之厚度為 2970 Α。依據上述,選用〇2MCF4氣體中之濃度大約為2〇%,並且 權衡蝕刻之等向效果(ERRg/b)與縱向蝕刻率(ERb),調整腔體壓力(cp) 大約為0.47托,因此,如圖7所示,對si〇2之縱向餘刻率(现)大約 為38 nm/min,而側向蝕刻率(ERa)大約為3〇 。等向性化學電 錄刻步驟先移除姓刻通孔332内之si〇2,其厚度總共大約為3577 nm’所需蝕刻時間大約為1〇〇分鐘,其蝕刻結果如圖北所示。接著, 繼續進行等向性化學電聚侧,以側向侧將第-金屬層331a下之 介電層311a與場氧層311b完全移除,其時間長度係依據侧通孔332 之間的金屬層331寬度,大約為%分鐘;同時,因基材31()之材料 主要為石夕’其以大約為35〇 nm/min之姓刻率被侧,最後形成一懸 置之多層微結構330,如圖3c所示。 圖8所示’為對稱多層微結構之殘留應力與祕高度的關係圖。 經由實驗’針對本發明製作之對稱多層微結構與習知技術製作之非對 稱多層微結構之_極端離況做分析。—種為非對稱結構最佳的情 況,所謂最佳情況係指各層㈣賊留應力均不受半導體製造過程^ 數的變異而改變,也不會受到後製程的影響而有所變動,另一種狀 況,是對稱結構最壞的情況,所謂最壞情況係指各層殘留應力的值會 隨者半導體製造過程的變異喊變,或是隨著後製程的雜而有所 動,使殘留應力的值隨著向上堆疊的層而增加。如圖8中虛線顯示, 在5〇〇 μιη X 5〇〇 μηι的平面下,非對稱結構於最佳清況依然會麵曲 201102340 5::而:然則顯示對稱結構在最壞情況T ,殘留應力可增加至 稱多層㈣射平坦。纽實驗可鋼本發日錄作之對 衡殘留應力,有效抑制魅曲問題。 味,述’本發明提供—種可平賊留應力之多層微結構製造方 層,·乡層微結構於—基材上,多層微結構包含複數金屬 射前輸間隔’並藉由絕緣層堆疊於基材上,金屬層係為圖案化 慎性、.·》構,妨複數_通孔,且金屬制並有金射介層包_ 刻通孔;接著執行-等向性化學電細,胸,移除糊通孔内之絕 緣層,及基材與金屬層間之絕緣層,以形成—懸置之多層微結構。因 基材與金制間找緣層被移除,縣之彡層微結胁直方向為一 對稱性結構,可平衡殘留應力,有效抑制翹曲問題。 ^The first layer of the insulating layer stack and the second metal layer (10) are separated from the second metal layer (10) and the first metal layer is patterned to form a plurality of gates: H patterned symmetrical structure; And, the first metal layer and the second metal layer=metal interposer surround each of the cut holes, and the insulating layer fills each sweet passer's performing-isotropic chemical "step", interposing with metal layer and metal The layer π ' removes the γ in the gamma through hole, and the first layer of the insulating layer S of the first surface layer and the storage layer is formed on the substrate. The suspended multilayer microstructure has structural symmetry in the vertical direction to balance the residual stress and effectively suppress the problem. An embodiment of the present invention uses a cavity pressure of a lower degree of vacuum to achieve an isotropic chemical plasma and adjusts the proportion of the reaction gas to increase the etching rate. [Embodiment] Figs. 3a, 3b and 3c are cross-sectional views showing a flow of a multilayer microfabrication method for balancing residual stress according to an embodiment of the present invention. The multi-layer microstructure manufacturing method of the present invention for balancing residual stress comprises the following steps. Referring to Figure 3a, a multilayer microstructure 330 is formed on a substrate 310. In one embodiment, the multilayer microstructure 33 includes a plurality of metal layers 33, a metal interposer 333, and an insulating layer 311. Continued above, please also refer to Figure 3a and Figure 4. 4 is a side elevational view of the metal layer 33Id of the uppermost layer of the multilayer microstructure, and FIG. 3a is a cross-sectional view of the structure along the line AA' in FIG. The plurality of metal layers 331 include a first metal layer 331a, a second metal layer 331b, a third metal layer 331c, and a fourth metal layer 331d, which are patterned symmetrical structures, and the metal layers 331a, 331b, 331c, and 331d are mutually The symmetrical pattern forms a plurality of etched vias 332. Please also refer to Figure 3a, Figure 5a and Figure 5b. Fig. 5a and Fig. 5b are shown in Fig. 5,023, which is a top perspective view of a second embodiment of a multilayer microstructure. A metal interposer 333 is disposed between the metal layers 331a and 331b, 331b and 331c, 331c and 331d, surrounding each of the etched vias 332. As shown in FIG. 3a, the insulating layer 311 fills the gap between the etched vias 332, the metal layers 33la, 331b, 331c and 331d, and the first metal layer 33la is stacked on the substrate 310 by the insulating layer 311. Referring to FIG. 3a, in an embodiment, the multilayer microstructure 330 is fabricated by a CM〇s process, and the metal layers 331a, 331b, 331c, and 331d respectively use a first metal (Metal 1) of a metal interconnect (Interconnect). a second metal (Metal 2), a third metal (Metal 3) and a fourth metal (Metal 4); the metal interposer 333 is a metal interposer (Vla) layer; the insulating layer 311 is used in an insulating metal layer. A dielectric layer 311a is connected, and a field oxide layer 311b of the CMOS transistor is isolated to cover the substrate 310. Moreover, in one embodiment, the materials of the insulating layer 311 and the substrate 310 are mainly cerium (Si〇2) cerium (Si). Then, an isotropic chemical plasma etching step is performed. As shown in FIG. 3b, the uppermost metal layer 331d and the metal interposer 333 are used as a mask for etching, and the insulating layer 311 in the remaining via hole 332 is removed, but a part of the metal layer 331 & The insulating layer 311 is interposed to maintain the stack of microstructures. • Again, as shown in Fig. 3c, the isotropic chemical electrical engraving step is continued to completely remove the insulating layer M1 between the first metal layer 331a and the substrate 31, and part of the substrate 31〇, splitting/ The suspended multi-layer microstructure 33〇' has a metal layer 331 symmetrically, so that the residual stress between the insulating layer 311 and the upper and lower metal layers 331 is substantially balanced with each other. The multilayered multilayer microstructure can be composed of at least two metal layers, followed by three metal layers, and so on. In the above embodiments, the materials to be used are (10) and & therefore, the chemical plasma gas Z is a reaction gas using a plate gas and oxygen (?2). The fluoride gas may be a halogenated carbon (Flu〇r〇Carb〇n) gas such as tetrahydrogen (CF4) or six gasified two carbon (C2F6) for raising oxygen atoms and fluorine radicals. Add a small amount of ruthenium 2 to the fluorinated carbon plasma to make carbon (c) and . The release of fluorine (F) neutral atoms and gas radicals can effectively improve the residual rate, 201102340 However, the concentration of 〇2 is too high, which will cause the surface of the material to be etched to be covered, resulting in a decrease in etching rate. The following examples use CF4 and helium 2 gases as reactive gases to illustrate how the present invention determines the gas ratio of 〇2 to CF4', but are not intended to limit the invention. Fig. 6 is a graph showing the relationship between the gas ratio of cf4 gas and the etching rate (EtchingRate, ER), wherein the legend of the Si etching rate (ER) is square, corresponding to the left vertical axis scale, and the Si 〇 2 etching rate (ER) The legend is a triangle, corresponding to the right vertical axis scale. It can be seen from Fig. 6 that when the concentration of 〇2 in the CF4 gas is between 10% and 40%, the etching rate is higher than that of the other concentrations, and etching is performed at a concentration of about 23%. The rate is the highest. When the concentration of 〇2 in the eh gas is between 5% and 1%, the etching rate is higher than that of other concentrations, and the etching rate is the highest when the concentration is about 1%%. Considering the selectivity to Si and Si〇2 during etching, it is preferable at a concentration of 5% because of a high ratio of etching rate (ER) to Si and Si〇2. An embodiment of the chemical plasma etching step is to adjust the cavity pressure to achieve an isotropic etching. The isotropic etching means that the lateral etching rate (ERa) is substantially the same as the longitudinal etching rate (ERb), that is, the etching isotropic direction. The effect willow tateRateRatio^ERR^) approaches i. The isotropic effect of etching (ERR- is defined as the lateral etching rate (ERa) and the longitudinal residual ratio (E is called the ratio. Figure 7 is not 'the Chamber Pressure (CP) for the Si〇2 The isotropic effect of the remaining moment (the relationship between ERIW and the longitudinal etch rate (ERb), in which the legend of the equi-directional effect y is square, corresponding to the scale of the left vertical axis, and the legend of the vertical meal rate (orphan) For the triangle shape, it corresponds to the scale of the right vertical axis. As shown in Fig. 7, the engraving rate (4) curve: The pressure of the cavity (CP) is reduced, that is, the cavity vacuum is increased, and the side rate (ERb) is higher. Therefore, in general, the plasma surname technique is to increase the quotation rate and maintain the reaction cavity at a higher vacuum. However, as shown in Figure 7, the equivalent effect of t Si〇K_ The cavity pressure (CP) increases, that is, the cavity vacuum decreases, and the isotropic effect (the ship ^ $ approaches 1. Therefore 'is the isotropic effect of the lifting side (ship one, the reaction chamber needs to be maintained at a lower level) The true line. In this implementation, for the ship-like isotropic effect (legs ^ between 〇w, the range of the cavity (CP) is set between 〇25~〇7 postal. Lower The cavity vacuum system is installed with a manual valve (Valve) through the intake end of the pumping pump to reduce the pumping capacity of the pump, so that the pump pumping and the incoming 201102340 gas flow rate are compared. Equilibrium is achieved in a low vacuum. The time required for the isotropic chemical plasma etching step can be determined by the thickness of the Si 2 to be etched, and the etch rate. Referring to Figure 3a, in one embodiment, the multilayer microstructure 33 The process is performed by a TSMC 0·35μπι process, in which the first metal layer 331a, the second metal layer 331b, the third metal layer 331c, and the fourth metal layer 331d are respectively interconnected by using MetalU, Metal 2, Metal 3 and the tearing material. The heights of the wires are 6650 A '6450 A, 6450 A and 9250 A respectively; the height of the metal interposer 333 between the metal layers 331a, 331b, 331c, and 331d is Ιμιη, so the thickness of the dielectric layer 311 is also ιμιη; The thickness of the oxygen layer 312 is 2970 Α. According to the above, the concentration in the 〇2MCF4 gas is about 2%, and the isotropic effect (ERRg/b) and the longitudinal etch rate (ERb) are adjusted to adjust the cavity pressure ( Cp) is about 0.47 Torr, so, as shown in Figure 7, for si〇2 The longitudinal residual ratio (now) is about 38 nm/min, and the lateral etch rate (ERa) is about 3 〇. The isotropic chemical electro-recording step first removes the si〇2 in the last-passed hole 332. The total etching time is about 3577 nm', and the etching time is about 1 minute. The etching result is shown in the north. Then, the isotropic chemical polymerization side is continued, and the metal layer 331a is placed laterally. The dielectric layer 311a and the field oxide layer 311b are completely removed, and the length of time is based on the width of the metal layer 331 between the side via holes 332, which is about % minutes. Meanwhile, the material of the substrate 31 () is mainly Shi Xi. 'It is sideways at a rate of about 35 〇nm/min, and finally a suspended multilayer microstructure 330 is formed, as shown in Figure 3c. Figure 8 shows the relationship between the residual stress and the secret height of a symmetric multilayer microstructure. The analytic multi-layer microstructures fabricated in accordance with the present invention were analyzed experimentally for the extremes of the non-symmetric multilayer microstructures produced by conventional techniques. - The best case for the asymmetric structure, the so-called best case means that the stress of the thieves in each layer (4) is not changed by the variation of the semiconductor manufacturing process, and it is not affected by the post-process, and the other is changed. The situation is the worst case of the symmetrical structure. The so-called worst case means that the value of the residual stress of each layer will change with the variation of the semiconductor manufacturing process, or the value of the residual stress will change with the post process. Increase with the layers stacked up. As shown by the dotted line in Fig. 8, in the plane of 5〇〇μιη X 5〇〇μηι, the asymmetric structure will still be in the best condition of 201102340 5:: and: then the symmetric structure is shown in the worst case T, residual The stress can be increased to say that the multilayer (four) shot is flat. New York's experimental steel can be used to balance the residual stress and effectively suppress the melody problem. Taste, the present invention provides a multi-layer microstructure manufacturing square layer capable of thief retention stress, a township microstructure on a substrate, a multi-layer microstructure comprising a plurality of metal pre-transmission intervals and stacked by an insulating layer On the substrate, the metal layer is patterned and prudent, and the structure is constitutive, and the number of holes is _ through-hole, and the metal is made of a gold-coated layer _ etched through hole; then the isotropic chemical is performed. The chest, the insulating layer in the paste through hole, and the insulating layer between the substrate and the metal layer are removed to form a suspended multi-layer microstructure. Because the edge-finding layer between the substrate and the gold system is removed, the 微 layer of the county has a symmetrical structure, which balances the residual stress and effectively suppresses the warpage problem. ^
201102340 【圖式簡單說明】 圖la、圖lb與圖lc所示’為習知非對稱性多層微結構之製造方 法之流程剖面圖。 圖2所示,為殘留應力造成mems裝置之勉曲現象示意圖。 圖3a、圖3b與圖3c所示,為本發明一實施例之流程剖面圖。 圖4為本發明一實施例之微結構其中一層之側視示意圖。201102340 [Simplified Schematic Description] Figures la, lb, and lc show a process flow diagram of a conventional asymmetric multi-layer microstructure. Figure 2 is a schematic diagram showing the distortion of the MEMS device caused by residual stress. 3a, 3b and 3c are cross-sectional views showing the flow of an embodiment of the present invention. 4 is a side elevational view of one of the microstructures of an embodiment of the present invention.
圖5a與圖5b所示’為本發明二實施例之微結構俯視透視示意圖。 圖6所示,為反應氣體比例與钱刻率關係圖。 圖7所示,為腔體壓力與蝕刻之等向效果及縱向蝕刻率之關係圖。 圖8所示,為對稱多層微結構之殘留應力與翹曲高度之關係圖。 【主要元件符號說明】 100 CMOS-MEMS 裝置 110'310 基材 111、311 介電層/絕緣層 312 場氧層/絕緣層 120 CMOS積體電路 130、 330 多層微結構 130’、330’ 懸置之多層微結構 131、 131a、331、金屬層 331a、331b、331c、 331d 132' 332 蝕刻通孔 333 金屬中介層 ERa 側向姓刻率 2011023405a and 5b are schematic plan views showing the microstructure of the second embodiment of the present invention. Figure 6 is a graph showing the relationship between the ratio of the reaction gas and the rate of money. Figure 7 is a graph showing the relationship between the cavity pressure and the isotropic effect of the etching and the longitudinal etching rate. Figure 8 is a graph showing the relationship between the residual stress and the warpage height of a symmetric multilayer microstructure. [Main component symbol description] 100 CMOS-MEMS device 110'310 substrate 111, 311 dielectric layer/insulation layer 312 field oxide layer/insulation layer 120 CMOS integrated circuit 130, 330 multilayer microstructure 130', 330' suspension Multi-layer microstructures 131, 131a, 331, metal layers 331a, 331b, 331c, 331d 132' 332 etch through holes 333 metal interposer ERa lateral surname 201102340
ERb ERR^ CP 縱向蝕刻率 蝕刻之等向效果 腔體壓力ERb ERR^ CP Longitudinal Etching Rate Isotropic Effect of Etching Cavity Pressure